Spacing control for telefacsimile systems and the like



Oct. 28, 1941. A. G. cooLEY 2,250,511

SPACING CONTROL FOR TELEFACSIMILE SYSTEMS AND THE LIKE 3 Sheets-Sheet l -I 1 u l l a l v l l l l J j l l V IIIIIIIIIIIIIIIIIIII .Sv NN INVENTOR.

Oct. 28, 1941. A. G. COOLEY 2,260,511

SPACING CONTROL FOR TELEFACSIMILE SYSTEMS AND THE LIKE Filed March 1l, 1940 3 Sheets-Sheet 2 @NOW IS THE TIME I I I NOW IS THE TIME I `VwILLIAM `IEx QUICK l THE QUICK BRowN l I l I THE QUICK BRowN l l luf-H11? v Jl I WILLIAM JEX QUICK @MUM- T WILLIAM JEx QUICK v THE UICK BRowN lv I THE QUICK BRowN I ,jl-WILLIAM JEL QUIQK I 1N VENTOR.

B? Mf- .och- 28, 1941. A G, COOLEY 2,260,511

SPACING CONTROL FOR TELEFACSIMILE SYSTEMS AND THE LIKE Filed March 11, 1940- 5 sheets-sheet :s

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1L/a I 35j a; 27 7 T3 E" INVENTO i BY mi ATTORNEY.

Patented Oct. 28, 1941 sPAcING CONTROL Foa TELEFACSIMEE SYSTEMS AND 'rmir LIKE Austin G. Cooley, New York, N. Y., assignor, by

mesne assignments, to Times Telephoto Equipment Inc., New York, N. Y., a corporation of New York Application March 11, 1940, Serial No. 323,366 28 ClamS. (C1. 1787.6)

This invention relates to Vtelefacsimile systems and more especially to methods and means for automatically controlling spacings between successive portions of a subject matter to be reproduced.

In certain applications of telefacsimile methods, for example in transmitting typewritten, printed or similar graphical representations, it is highly desirable to be ableto vary the spacing between successive reproduced lines independently of the character or size of the actual transmitted graphic matter. Thus in the case of matter transmitted for newspaper work or the like, it is very desirable to have. the successive lines of the subject matter at the transmitting scanner as close as possible so that unnecessary line time may not be consumed in scanning the blank spaces between lines. In the case of typewritten or printed subject matter to be transmitted, the message or other subject matter is preferably imprinted with single space between successive lines. However, at the receiver, such single spacing may not be desirable, especially where the subject matter is to be edited directly from the reproduced copy. Accordingly, the `present invention provides methods and apparatus whereby typewritten, printed or similar subject matter can be scanned in the normal way at a transmitter, and at the receiver the spacings between successive lines or portions of the reproduced subject matter are automatically controlled so as to provide double, triple or other desired spac- The invention is in the nature of an improvement on the system disclosed in my prior Patent No. 1,719,392. The system disclosed in said patent requires the provision of special marks in the space between successive messages or subject matters 'to be transmitted, whereby a special spacing signal of a predetermined frequency is transmitted. It is one of the principal objects of the present invention to effect the automatic spacing at the receiver without requiring a special frequency signal and without requiring a tuned relay or the like at the receiver. In accordance with this object, it is not necessary to` employ special markings or scanning arrangements at the transmitter.

A feature of the invention relates to a facsimile reproducing mechanism which effects any desired spacing between successive portions such as those between successive typewritten or printed lines, and without requiring'a special arrangement at the transmitter.

simile transmission of graphical subject matter such as writings, printings, etc., whereby the subject matter may be scanned with single spacing between successive lines and reproduced at a receiver with double, triple or other desired spacing without affecting the size or character of the actual reproduced subject matter.

A feature of the invention relates to a special form of spacing discriminator circuit which may be used with a facsimile receiving or reproducing machine to control automatically the spacing between successive portions of an originally transmitted subject matter.

Another feature relates to a facsimile reproducing machine having' paper or web-feeding mechanisms of different throws vor indexing ratios, one of said mechanisms`being effectivey to advance the web normally` at an elemental scanning line unit speed in a direction substantially perpendicular to the transversev scanning motion of the reproducing scanner; and the other mechanism being automatically effective to advance the web a distancecorresponding to a number of elemental line scanning units When no facsimile signals are being received.

A further feature relates to a novel form of timing relay for use in conjunction with a motor driven web-feeding mechanism of a facsimile machine.

A further feature relates to an automatic spacing mechanism for use with a telefacsimile receiving machine, which` mechanism does not depend upon a special frequency signal for controlling it. As a result, the possibility of false operation of the automatic spacing mechanism is reduced, especially where the machine is to be operatedover atelegraph ortelephone line.

- A still further feature relates to the novel organization, arrangement and relative location and interconnection of parts which constitute an improved automatic spacing control for telev facsimile receivers orthe like.

Other features and advantages not specically enumerated will bey apparent after a consideration of the following detailed descriptions and the appended claims. l Y

y In the drawings whichrepresent certain preferred embodiments of the invention,

Fig. 1 is a'schematic diagram vof a telefacsimile system embodying featuresA of the. invention.

Fig. 1A represents aL typical subject matter as scanned a-t the transmitter of Fig. 1.

Fig. lB'shows the telefacsimile reproduction of Fig. 1A in accordance with the invention.

yAnother feature relates to a method of fac- 5.5 Fig. 2is a schemati'ckwiring diagram of the ta'tes the drum I through suitable gears 'I.

a result the lights and shades'of each elemental area -in successiveelemental scanning lines Aof the subject :matter -on drumfl .aretranslated into corresponding electrical 'potentials' by cellA 4 'as is well-known inthe facsimile art. During the 2Mb" `n`.

receiver of Fig. 1 embodying features of the invention.

Fig. 3 shows an alternative form of spacing control circuit that may be used in the system 'of Fig. 1.

Fig. 4A shows'an alternative 'form of originalv 'subject matter v.which may be used in practicing the invention.

Fig. 4A in accordance with the invention.

Figs. 5 and 6 show two additional'rnodiriicationsv of the invention. i

While the invention will bedescribed herein aslL 'A embodied in one particular form 'of telefacsimilel system, it will .be understood thatin certain of `are applicable'to other systems.; '13;

well-known form. of" telef-acsimile,.scanning mechanism ldiagram'matically1l .represented l as being mounted ona carriage 2, including amongst other things,v a. light source 3vand al light-sensi tive cell 4. The ,light cell. andlight source are arranged to be moved as a-"unittransverselyl of` the drum in the -direction'of vthe-dottedlarrow,`

under control of fa motor 6,, while motor 5 roscanningof Ieach Aelemental' transverse linear element' ofV the subject matter, the carriage 2 is advanced by'motor Bin'the directionoi the dot-` ted-line arrow a unit distance substantially equal to the width of an elernentalscanningy line.

Thus, if the subject Vmatterfis scanned by the light 3 in transverse lines-of approximately 0.01 inch width, the drumv I'is'fadvanced by motor 5 approximatelyfOl inch. per revolution. Preferably, although notinecessarily, the carriage 2 v ismounted forl vsliding movement on a pair of` fixed parallel rails or guides 8, and has fastened thereto a exible metal orfabric band 9 which has the other end fastened to a drum or wheel I0, after passing around the idler roller II.`

Wheel I0V is driven iat the .required speed .by motor 6 through a-siiitable vvormr'andv wormits aspects the several features of the invention fore supplies a sustained lcarrier Wave, for example 1800 C. P. S. to the amplifier-modulator I'B which is also excited under control of cell 4. Consequently, when the subject matter is being scanned, there is impressed upon the line L, an alternating current of substantially constant fre'- quency which is modulated by the facsimile signals from cell 4.

Fig. 4B shows the telefacsimile,reproduction of? 'TIL' rAt the receiving station, the modulated carrier is amplified and demodulated in any suitfableV arrangement I'I, whereby the original facsimile signals are reproduced. The facsimile sig-` nals are then` amplified in the high voltage genjerator I8 asdescribed in Patent lNo. 1,702,595, -the output of which is used to lcontrol a recording lamp or tol energize a recording stylus orv A l needle Vwhich forrnspart of the facsimile recording scanner mechanism. This mechanism may be of any well-known type arranged to be moved transversely of therecording web I9 by a motor 20, which is synchronized in any well-known manner .with-motor 5, so that vthe drum I rotatesv in rsynchronisrn with the movementof the recording needle transversely of web I9. As shown in the drawings, the scanning mechanism. may be inthe formofa nat endless metal band l2| carrying one or more pointed electrodes or needles 22, the point vof which is .in'close` proximity to the recordingr web I9. Mounted on the opposite` side of web I9- in alignment withthe moving needle 22'1 is a continuousfconductive stripr 23 extending the width of web I9. Preferably, although not necessarily, the web I9 bears against. they surfacel of electrode 23. which is f charge of corresponding inten-sity to be producedr wheel I2 vor other ..speedl, reducing mechanism..

When the carriage 2 has reached'the eind of its travel in thedirefction 'off the arrow, it fcauses a pair of Vcc'intacts I3 to'be automaticallyopened to break the power circuit, to motor 6. A spring I4 has oneend fastened to carriage 2 and the other end fastened to'afxed. support so that` when the motor circuit is broken, the said spring f returnsv the carriage to its initial position in readiness for the next transmission. .If desired, Y]

one or both of the rails may., be in the form of a rack, and a pivotedrpawl may be carried by carriage 2 as to prevent any'accidental return movement of carriage .2 during scanning.

When the carriage, hasr completed its/scanning movement, the, pawl may be'v released vmanually or automatically byv engagement with a .suitable stop Wherebythe spring id 'effects' the' carriage return. Itfswill be understood of course,` that any well-known feed mechanism may be employed for .moving the carriage between .each line scanning.

.' I'he motor` ,5, controls the scanning drum l I also drives an A. C. generator I5. which theremounted in a vsuitable insulating support 24 as shown whereby it is insulated fromthe `metal parts of the ma-chine to prevent undesirable sparking. Electrode. 23 is provided with a con# ductor 25 which-maybeconnected to ground or. other suitable "steady lbase potential. One of the rollers 26 is driven from the motor 20 through -a suitable speed reduction Vgearing such as the- A suitable' worm and wormwheel as shown. brush 2'I'makes contact with the band 2| andis connected tothe conductor 28 which is con, nected to the output of high voltage corona gene. Thus the.,high volta-ge signals im-f erator I8. pressed von needle 22 cause a minute corona disat the point thereof which discharge acts on ythe successive elemental areas of web I9 in the man-x ner described in my prior Patent No, 1,702,595.,

In order to advance the web I9 inthe Adirection of `the full-line arrovv, there is a motor 29 con-v` 'nectedthrough suitable gears tothe drum `or` ItA will that the subjectmatter will be reproduced line for line, consequently if the successive linesoA the original subject matter are 'single'spacecL as represented 'by the spacing a--b of Fig. 1A, then they would ordinarily rbe reproduced with a 'similar single spacing. However, if it is desired toy re-k produce the linesr with double' spacing or any other multiple spacing as represented by a-b of Fig. 1B, a portion f the incoming currents, after passingl through low-pass lter l3| are amplified scanned line. l4| receives ,-afcharge' 4of the desired level vand ythrough lclutch 36 :to the shaft 34. :so-geared Ato shaft 34- that when itis operated,

theV device 33fis of such a character that when no letters vror similar subject matter are being transmitted 4for a certain -length of time, a 'special spacing impulse is derived locally at the receiver, whereby `the web VI9 is advanced automatically a vdouble or multiple space as desired. For this purpose, the platen shaft 34 iscoupled to an auxiliary motor 35 throughl a clutch 36, and motor 35 is energized vfrom the local supply source 31to advance the recording web the requireddistance. Preferably, in order to control the auxiliaryspacing operation more accurately, the space discriminator means has associated therewith `a timing arrangement to time the duration of the spacing operation. This special 'timing arrangement is indicated schematically by vthe block T38.

Referring to Fig. 2, there is shown in schematic form, a space control arrangement corresponding in general to the portions 3l to `38 of Fig. 1. The received facsimile signals in the form of a modulated audio -frequency carrier current are received from lline L, vand after amplification indevice I'1, -are passed through the low-pass filter 3l and thence to the amplifier 3'2. The low-pass filter distinguishes `lthe"' low vfrequency facsimile signals "from the steady-state carrier so that the amplifier .32 lis excited substantially only by the said low frequency facsimile signals. Consequently, as long as the transmitter is scanning a line of subject matter having shadevariations in successive yelemental areas, the loutput of amplifier 32 consistsrof a rapid succession `of relatively low fre- Iquency signals representing the original scanned fareas. The outputcf amplifier 32 is transferred "by transformer .39 toa rectifier Acircuit including .rectifier 40, condenser 41, resistor42 and resistor,

l43. Resistor 43 servesfto 'retard the charging of condenser -4I so that said condenser is not charged to the desired control level byv one, or a few single or miscellaneous impulses.v However,

,when :an elemental line ofsubjectmatter such as that :shown inFig. 1A is being scanned, the tube v40 will be 4subjected to a relatively great number -of rsuccessive impulses representing the shade values of the successive elemental areas ofthe Under this condition, .condenser lthereby maintains a suitable bias on 'the control- -grid 44 lcf l.a `space 'discharge tube I45, "whereby anode-cathode current is fprevented from flowingi YConsequently,'so.long as a variable shadeisubject lmatter is being transmitted, insufficient ,current Iexists to energizerelay windingf46, with the.re-

scanned, the incomingwcurrents from line L will ...besubstantially a uniform amplitude audio `frequency current with the result that `no impulses will be produced inthe rectifier circuit andthe lchargegon condenser -4l will leakzol'thus removingl the blocking bias from control vgrid -44 and -`allowing the plate current of tube l45gtoclose the vcontacts 41 of relayf46. of .contacts '41 may completeazpower circuit di If-desired, ythe closing rectly to the auxiliary motorl 35 vwhich is coupled Motor 35 'is it' feeds the web 19' a distance-which is amultiple :of the distance ,a-b (Fig. lA), and `preferably in 'the samey timer-that.y `is required for scanner 2 tolscan the space c-b lat the transmitter. Instead0f `using a motor to `effect themultiple or yrapid spacing of the web .19, the relay contacts 4.1 may control a suitable ratchet and pawl combination coupled to shaft 34.`

l Preferably however, where the spacing is effected by auxiliary 35 motor, there is provided a timingrelay circuit 38. 'I'he shaft of motor 35 in addition vto being coupled to shaft v34 through the clutch 36, is also provided with a worm 50 which drives .a wormwheel `5I to which is fastened the circular metal kdisc or drum 52. Member 52 has an insulator segment 5.3 set in its periphery, land cooperating `with said periphery is a shiftable Ibrushlllmounted in a brush-holder 55 whichv is controlled by the pivoted armature 56'zassociated with an operating vmagnet 51. Norm-ally, magnet '51 .is deenergized so 4that the retractile spring 58 maintains brush vv54 in engagement Awith the Vin,- sulator segment `5.3. Associated with disc 52is another wiper brush .59, whereby the circuit from .powerzsource 31 can be completed through motor 135. The completion of thiscircuit is controlled by: relay .46 which in turn responds to the scanning Aof a continuous space at the transmitter, for example .that corresponding to the space d b (Fig. 1A). v6D charges through resistance 6|. The power for 'operating the armature 56 is supplied primarily fbythe charge on condenser 60. In other words, :the armature 56 is operated by the magnet 5i .only when facsimile signals are not transmitted forapredetermined length of time, correspond,- Aingfor example to the time required to scanone revolution of the drum l. .power fisabsorbed'from condenser 6U, lmagnet 51 As soon as ,most of the :through winding 51 before the condenser 60 attains the desired operating potential.

Brush 5.4 is arranged with respect to segment 53 lso thatwhen armature 56 is retracted by spring 58, it is normally insulated from disc 52. However, when .magnet 51 operates, brush54 is `,moved suiciently to cause it to engage the confducting periphery of 4disc 52, thus completing the circuit to motor 35. After disc 52 has made a complete revolution, it will then come to rest speed of .disc 52 is proportioned to thecapacity lalmost entirely discharged and .armature 56 is retracted, consequently the ldisc 52 remains in fits normal position as shown, even though relay 46 is still in its operated condition. The motor 35' therefore remains stationary until the next line ofprinted or other subject is scanned. As soon as the next succeeding line of subject -matteris so scanned, relay contacts 41 are-opened thus -frestoringthe timing circuit to a condition .to be reset when the lnext space between lines vis scanned.. When such next space is scanned, rellay-contacts41-again close and the timer 38 goes through the same cycle of operation as above. y EWhile yin Ithe foregoing description of Fig. .2,

While contacts 41 are open, condenser shade' between the lines( In other words, ,the 1 spacingcontrol unitv of Fig. 2 discriminatesbey tween, substantially continuoussignal impulses l corresponding to a. uniform shade-across theY web :as distinguished from irregular impulses corresponding'to subject matter being scanned. lInstead of relying `upon this method of discrimina-.-

tion, the l space indicator unit 33"may be designed so as to distinguish -between a continuous positive Isignal .and a continuous negative signal or between a continuous strong signal and .a continuous weak signal.- -Inorder to effect this result.' thespace between'successive lines may be divided transversely into twosections, one of 5which Vconsists of a continuous black strip and the Bother of-a continuousv ywhite Strip. One practical way .of achieving'this result is shown f in lFig. 4A, wherein the original subject matter l individual character and space slugs on the -typewriter printing bars may have set into' them beneath the characters, individual underscoring vmarks so that as each character is typewritten,

`a. simultaneous underscoring is applied resulting in -av continuous underscoring across' the sheetr It will be understood of course, that the subject matter may be typewritten or printed in the con` ventional way and the underscoring may be applied in a separate operation by an underscoring key or'the like. Y

The original subject matter of Fig. '4Ajis scanned by the transmitter of Fig. 1 andthe .printed subject matter `is reproduced at the receiver of` Fig.v 1'- in the form illustrated inl "Fig.f41r3. However,v in order to utilize the under-` ;scoring 63v tocontrol the spacing discriminator,

f thelattfer-may be of the type shown in Fig. 3.` l'The `signals representing the printed subject 'Frnatter are received from the line L and passed i4fth'rung-hthe amplifier I1 and the high or corona "jvltage generator I8 to control the recording mechanism 64' similar to that already described Airrc'onnection -with Fig. 1. lola'ckline-'63` is scanned, a corresponding con- Ftinuoll's'strong lsignal is applied to the grid 65 of faniplifler tube 66 resulting in the building-up of 4la corresponding charge on storingcondenser 61 f'wliich'jisconne'cted in circuit with the recter tube 68. The :polarity` of this charge-as applied `-to`ithe`fcontrol grid 69 of tube 10 is suchl as to `cfause suiicient plate current to flow through 'saidgtube 10 tooperate the vcontacts y41 of the 'vrelay'46.v Normally the control grid 69 is biased clos'to' plate current cut-,off by means of the fbias'battery- 1I so that as long as v'printed Vsub-` fject'matter-or the like isbeingscanned, relay g'conta'cts-41remain open.A However, as a result off the 'scanning of line `63 as above described,

the negative bias on grid 69 is overcome by the 4positive 'charge built-up condenser 61, causing -contacts 41 to close. Contacts 41 may control ap-'timing arrangement similar to the v'arrange-- .-,rnent-38pfFigs- 1 and :2. vIn the embodiment When the vcontinuous j .of Fig 3, since the-discrimination .is eiectedfl mainly Icy-signal level, xno lowfpass `iiltercdrrei,i sponding'to the filter 3`I of Figs. 1 and.2,is re-5 quired. .It will be, understood of course that the constants of the rectifier and condenser charg-1 ing 'circuits are yso chosen thaty when-printed or similar-subject -rnatter is being scanned, `there is insuflcient` positive vchargebuilt-up on con- `denserl to overcome the cut-off bias on grid 69.

It .will be understood of course that inthe foregoing arrangement particularly where` the subject matter being transmitted is singlerspace lcopy that it is necessary-to'rnount-the sheet or other subject matter ondrum-I at the transmitter so that, the individual linesland spaces surround the drum so that the `boundaries of the,

line spaces are located, in planes Aperpendicular I to the drums rotational axis. In otherlwords so that the beginning and end of each line are in circumferential alignment aroundthe drum I.

Various changes and modifications maybe made in the several Vembodiments withoutdeparting from the spirit and scope of lthe invention. Thus, while the original subject matter of Fig. 4A is provided with a continuous underlining 63, this underlining may consist of a series of spaced dashes or dots which are of regular spacing so as to control the production of the necessary positive grid bias applied to grid 69 by condenser 61 (Fig. 3). l

Furthermore, while Fig. 1 shows sa scanning system at the Atransmitter wherein the subject matter is wrappedA aroundgthescanning ,drum

I, it Will' lbe understood that an endless belt scanner may be employed as. disclosed in said Patent No. 1,719,392. Furthermore, while the space discriminator 33 is `shown only at the receiver, a similar arrangement may be used at the transmitter to control an auxiliaryline feed motor and clutch-arrangement .(not shown)` similar to motor 35 and clutch 36 (Fig. 1).,

, Likewise, while thel signalshave been described as transmitted by means ofan audio frequency carrier, they may-.alsol be transmitted as modu-yy lations lof a radiov frequency carrier or if desired.

they may. be

transmitted z directly vwithout ya carrier. -l x.:

Referring .to Fig. 5,"there shown a modi- Y cation of. the `invention wherein the spacef dis` j criminator arrangement islocated at the transmitter, in order to reduce the cost of the receiv- 1 ing equipment. This is of importance where la lcentral transmitter. is employed .feeding a..plu rality of separatereceivers. In Fig. 5,1.theparts which correspond to .those of Figs. 1 and 2, bear the same designationnumerals.V The facsimile transmitting scanning mechanism similar to that of Fig. 1, isdesignated generally by numeral-100, and while only thev light-sensitive 'cellj4 and the drum-driving motor 5 and carrier generator I5 areshown, it will beunderstoodrthat it includes other partsrcovrresponding to those designated vI to I5 in Fig. 1.'. The low-.frequency facsimile sig'- nalsfrom cell 4 areimpressed upon the :ampli-V ner-modulator I6`asabovedescribedl A portion of the outputf ofamplier I6 is' fed through fa low-pass lter 37| and an amplifier 32"'to a space discriminator 33 similar t'o that of Figs. 1 and 2.

Only the contactsIlly ofthe relay 46v arel shown.

Contacts 41 are f normally open so long as variable shade subject matter such as printed matteris 4 being scanned. I-Iowever, when a linespacehas been scanned, relay contacts 41,*close as described above under control of elements: ,40 to `45 .inclusive. These contacts connect a source 10| of low frequency alternating current;A to the -modulator IS. y Thus, when a line space is being scanned, the current on line L will consistof an 180|)` C. P. S. signal modulated by the low fre'- quency signal e. g., 300 C. P. S. from source The 300 cycle signal is received and amplified in the device associated with the receiver and` is passed through a low-pass filter |02 to operate contacts |04 of the tuned relay |03. Contacts |04 complete the circuit from the power source 31 to the auxiliary motor 35 which is coupled through a clutch 36to the shaft 34 of theplaten feed motor 29. The facsimile signals are also received and amplified in device l1 and are .applied to the'high or corona voltage generator I8 associatedwithythe reproducing scanning equipment |05 similar to that of Fig. l. The motor 20 for operating the recording needle `is also shown in Fig. 5. With the arrangement of Fig. 5, the recording web is'advanced in synchronism with the transmitter, but when a line space is being scanned at the transmitter, the motor takes control to feed the web a multiple spacing distance as `above described. y

, Instead vof employing a low frequency alternating current to control the motor 31 (Fig. 5),

a direct current may be employed for the purpose. ySuch an arrangement is shown in Fig. 6 wherein the parts corresponding to those of Fig. 5 are designated by. the same numerals. The relay contacts 41 in this embodiment instead of applying a low frequency` control signal to. the modulator I6, serve as a reversing switch for applying oppositely polarized currents to the line L. Thus when printedv subject matter is being scanned, relay contacts 41 connect the positivebattery |06 to the line, but when contacts are operated Ias a result of a line space being scanned, the negative battery |01 is connected to the line. This negative battery operates the polarized relay |08 at the receiver Which thereupon closes the circuit for the spacingmotor 35.

What I claim is: f l

1. In a system for transmitting visible representations to a distance, a transmitting scanner for scanning subject matter arranged in` transverse bands with successive bands spaced a certain distance from each other to transmit electricV signals representing said bands, means controlled by saidy signals to reproduce said bands, and means controlled by the absence for a predetermined time of signals representing said bands for spacing the reproduced bands a distance which is` grea-ter than said first-mentioned distance. v

In a systemfor transmitting visible repref sentations to a distance, a transmitting scanner for scanning subject matter arranged in trans,- verse bands with successive bands spaced acertain distance from each other to produce facsimile signals representing shade variations of successive elemental areasin said bands, means controlled by said signals to reproduce said bands, and -means to vary the spacing of the reproduced bands with respect to thespacing of the original bands, the last-mentioned means including a control device Which responds selectively rto the absence for a predetermined length of'time of signals representing subject matter in said bands.

3. In a telefacsimile system, meansA `to scan a subject to produce facsimile signals representing spaced lines of variable-shade subject matter each line representing a relatively great number of shade transitions over its length, said means also producing other -signals representing spaces between said lines, said spaces having relatively` few 'shade `transitions over their length, .l means controlled by the first-mentioned signals` said lines but with a different line spacing fr'ornl the original subject, the last-mentioned means: including reproducing scanner means and-line. feed means'and a device local to the receiverand'. selectively responsive to ythe scanning of .thex spaces at the transmitter for varying the Operation of said line feed means at the receiver with respect to theline feed means at lthe transmitter.

, 5. In a system for transmitting visiblefreprea sentations to a distance, meansy for scanning af subject having spaced transverse lines to .produce facsimile signal currents,- f wherein. the scannedlines are represented by current modulations and thescanned spaces are represented by the absence of current modulations, telefacsimile recording means controlled by said current modulations to reproduce said lines and spaces,

and means yselectively responsive to thescanning' of 'said spaces, for varying the spacing of the reproduced `lines with respect to the originallinc spacing,l r

`6.',Inv a telefacsimile system, means to scan av subject .comprising transversebands of variable shade' areas, and an intervening band of `substantially-uniform shade areas to produce cor-y responding facsimile current signals, facsimile recordingfmeans to reproduce said subject under control of said signals, the last-mentioned means includinga recording web, means'to feed said- Web normally a distance corresponding to the. Width of an elemental scanning line, a space discriminator control arrangementV for controlling the feeding of said web a distance different from said normal distance and means responsive to the scanning. of saidintervening band for producing therefrom a substantially steady state signal of suflicient predetermined minimumA duration to, control said space4 discriminator arrangementmoving said web a distance which is greaterthan the width of said intervening band. 7. Ina telefacsimile system, means to Scanl'a subject having a transverse rband of .variable shade areas and' a band of substantially uniform shadeareas to produce corresponding facsimile current-signals, the widthsof said .bands having ayfxedy ratio, facsimile reproducing means 'controlled by said signals to reproduce said bands with the ratio vof Widths ofthe variable shade bandsk and the uniform shade bands `differ-ent fromv the first-mentioned ratio, the last-mentioned means including a devicefselectively responsive to a substantially steady` state spacingcontrol signal produced bythe scanning of said uniform shadeband. r

i 8. The method of telefacsimile transmission of subject matter with transverse bands of close spacing between bands, which includes the Steps of scanning the transverse bands, scanning the space between bands, electrically reproducing the bands in successive.linear elementstransversely t of a recording medium, automatically increasing the space between the recorded bands as compared with theL space between the bands of the original and under control of a substantially steady state signal condition produced by the scanning of said spacing in the original subject matter. y

9. 'Ihe method of reproducing a printed or similar subject matter by point-by-point scanning and with different line spacing in the reproduction as compared with the line spacing in the original, which includes the steps of scanning the lines and spaces at a transmitter, and locally at the receiver detecting the reception of a substantially steady state signal condition prothe transmitter by transmitting a substantially.

steady state signal produced by the scanning the said interline space.

1,1, In a telefacsimile system, means to set up `in a receiver variable-condition signals corresponding to' variable shade areas of an original subject matter to be reproduced and other` substantially steady condition signals representing spacing between portions of said` subject matter, and means to translateboth said signal conditions into a reproduction of said'original subject matter, the last-mentioned means including an arrangement which is selectively responsive to said steady condition signals to vary the size olf the reproduced spacing with respect` to the spacing in said original subject matter. 3

12. A telefacsimile system according to claim 11V in which the said translating means includes a recording web having means to feed the web` at a uniform' line scanning rate so long as said variable condition signals are being set up, and other means to feed said web at a diifer'ent rate when said uniform condition signals are being set up.

13. A telefacsimile system comprising a telefacsimile transmitter, a telefacsimile receiver havingmeans to reproduce printed 4or. similar subject matter with Adifferent line spacing as compared with the original, the last-mentioned means including aspace kdiscriminator comprising a signal storing arrangement, a line feedy ar.- rangement, and circuit arrangements for operating said' line feed only when the saidstoring arrangement receives a substantially continuous signal for a predetermined duration. 14. AA telefacsimile system according to claim 13 in whichthe signal storing arrangement comprisesa condenser and rectifier operated under control of said signal. l j l .15., A telefacsimile system according to claim 13 in which the said storing arrangement conl-y trols a grid-controlled discharge tube having its control grid normally! biassed to plate current cut-,off under control of said storing arrangement. e n i 16. A telefacsimile system comprising a telefacsimile transmitter, a telefacsimile receiver having line feed Vmeans operable at two different Lib rates, and meansresponsive to the scanning of a spacing Vbetween lines of'printed or similar subject matter'at the transmitter for selectively operating said feed means at a different rate from its normal line feed scanning rate, the last-mentioned means including space 'discriminator' means to detect signal conditions corresponding to the scanning of said spaces at the transmitter and a grid-controlled discharge tube which'is biased to plate current cut-off when printed or similar` subject matter yis being scanned but which passes plate current under control of sai spacel discriminator means. 1

17. A system according to claim v16 in whichV said detecting means includes a condenser for controlling the bias on said grid, and a resistance in circuit with said condenser for preventing said bias being reduced to a predetermined level eX- cept when a substantially continuous line spacing has been scanned at the transmitter.

18. A system according to claim 16 in which said detecting means includes a lrectifier energized by the signals from the `transmitter and a condenser which is connected to said rectiiier to facsimile transmitter, a telefacsimile receiver l controlled by said transmitter and having means to produce different line spacing as compared with the line spacing of the original subject matter at the transmitter, the last-mentioned means including normal scanning-line feed mechanism and auxiliary inter-line space'feed mechanismfa space discriminator for detecting a signal condition corresponding to an interline space, Ymeans controlled by said discriminator for controlling said auxiliary feed mechanism,and a timer device for rendering said auX- iliary feed mechanism ineffective until said signal condition persists for a predetermined mini; mum time interval. v 20. A system according to claim 19 in which the said discriminator 'is selectively responsive to the scanning of an inter-line space of the original subject matter as compared with the scanning of the subject matter proper, and said timer includes a device which is set intooperation only when said signal condition persists for said predetermined minimum time interval. 21. A line feed arrangement controlled by received facsimile signal currents for controlling the automatic line feed mechanism of a telefacsimile receiving machine, comprising a motor for operating said mechanism, a power circuit for ,said motor, a rotatable timing member "driven by said motor, and means selectively responsive only to the receipt of line fe'ed signals beyond a predetermined minimum timey interval to close the circuit of said motor under control of the timing member.

l22. A timer according to claim 21 in which th'e rotatable timing member is in the form of a commutator, 'and said selective means includes a shiftable brush which is arranged to be operated toclose the motor circuit through said coml mutator after said predetermined time.

23. -A timer according to claim 21 yin. which said selectively responsive means includes a relay -having its Winding connected in circuit with a condenser, and a selectively operable switch is provided for discharging the condenser through said winding upon receipt of spacing signals. f 24. A space control arrangement for telei of a line feed mechanism at the receiver under Afacsimile receiving machines, comprising a gridcontrolled tube, a condenser connected to the grid of said tube to bias it to plate current cutoi so long as printed or similar subject matter is being scanned at the transmitter, a switch operated by said plate current, a line feed mechanism for eifecting spacing at the receiver, means to operate said mechanism at a normal rate corresponding to the width of successive elemental scanning lines and for operating said mechanism at a diil'erent rate of speed corresponding to inter-line spacings of subject matter, a timing control for determining the operation of said mechanism for inter-line spacing, a switch for controlling said timing control, a normally charged condenser, and a discharge circuit for said condenser including contacts of the first-mentioned switch and the winding of the second-mentioned switch, said switch being energized under the control of the discharge of said condenser.

25. A space control arrangement according to claim 24 in which the charging circuit of the second-mentioned condenser includes a resistance having a value which is correlated to the discharge time of the first-mentioned condenser whereby said line feed mechanism is rendered effective only when a line spacing has been scanned at the transmitter.

26. The method of reproducing single space printed or similar subject matter by tele- Y control of said signals.

27. The method of reproducing single space or similar subject matter by telefacsimile with different line spacing from the original, which includes the steps of providing the space between the lines of the original with two sharply contrasted transverse bands, scanning said bands to produce corresponding spacing control signals of contrasting characteristics and of substantially steady state character, applying said signals to control the charge and discharge of a condenser, and thereby to control the on and off condition of a line feed mechanism.

28. A telefacsimille system comprising a telefacsimile transmitter having output terminals and means to scan printed or similar subject matt-er to produce facsimile signals and impress them on said terminals, a space discriminator local to the transmitter which responds selectively to the scanning of spaces between lines of subject matter, said discriminator including a devi-ce which is maintained in one condition so long as said subject matter is b'eing scanned and in another condition when a space between lines of subject matter is b'eing scanned, a source of spacing control signal having a characteristic which is different from that corresponding to the scanning of said subject matter, means controlled by said discriminator to connect said source into circuit whereby said line-feed signal is impressed on said terminals, a telefacsimile receiver having line feed mechanism including means to advance a recording medium at one rate as long as said subject matter is being reproduced and at a different rate when line spacing is to be effected, the last-mentioned means being selectively responsive to said line feed control signal,

.AUSTIN Gr. COOLEY. 

